Process of producing new refractory material for the manufacture of insulators and other uses.



UNITED STATES.

PATENT OFF-E) PROCESS OF PRODUCING NEW REFRACTORY-MATERIAL FOR THE OTHER USES.

-Specification of Letters Patent. Application filed m 25, 1905. sl in No. 262,262.

MAPiUFACTURE 0F msumoas AND lPatent'ed March 27, 1906. s

To all whom it mag concern.-

' Be it known that I,. DEMETRIUS M. STEw-. ARD, of Chattanooga,

State of Tennessee, have invented a Process for Producing a New Refractory Material for the Manufacture of Insulators and other Uses,

moisture, ispeculiarly manufacture of insulators for electrical or- S -ture steatite is a of which the follo ,is a specification.

My present invention relates to the productlon of a new refractory material which, possessing, among others, the qualities of high non-conductivity, rfect resistance tot e effects of heat and cold, and resistance to adapted for use' in the other p In myapplication for United States Letters Patent No. 145,081, filed February 23, 1903, I have described a material,

hereinafter designated fmy compound,

which possesses, among others, the qualities enumerated.

My. compound is a complex anhydrous bisilicate having for its constituents silica combined with such oxide as are essential to the combination. In the manufacture of my compound I ordinarily prefer to employ as the basic materialthat is to say, the element which afiords chiefly the silica of the combinationthe.hydrous magnesium silicate commonlyknown as talc, steatite, orsoap stone and with the same a suitable proportion of water-glass, sodium silicate, or potassium silicate or double water-glass composed of sodium and potassium silicates or alkaline silicates richer in silica or mixed with silica or their equivalent. There is a group of silicates each of which has a close resemblance one to another and of which as foundin naample. For convenience, therefore, the term steatite as employed herein is used to designate conventionally all substances of the same general description and characteristic qualities, including pyrophyllite, although it is a hydrous silicate of aluminium. From a mixture of magnesium silicate or Water-glass, as hereinafter specified, the prod-' uct obtained by my process exhibits as con-- stituents the presence of sodium and magnesium oxide, as well as of aluminium oxid. I regard the presence in the compound referred to of, sodium and magnesium oxide as essentialto the combination. The aluminium oxid in that compound I regard as an adventitious quantity, present therein by reason, perhaps, of impurity in the basic material of the mixcounty of Hamilton,

' than an economical expedient.

art or process from which fairly representative exture from which it is produced. Ifa silicate of aluminium were employed asthe base, which is suggested the practice of my process, the forego' statement might not in that instance be ap- .plicable. I The presence in the aforesaid prodnot of that which is and chemically ineffective suggests the ractice which has been in some instances ollowed by me of introducing to commercial advanta e into the manufacture other corresponding yinert substancessuch, for example, as s employed to give bulk to the mass or my c0mpound at a proportionately insignificant increase of cost without injury to the'product in'respect to certain determinate uses. For many purposes such an addition would constltute an adulteration-of the product and should of course be therein avoided; but for other purposes it may constitute no more In respect to the product, as well as to the process, such addition to the mass is of the nature of mere sur lusage or make-weight in the roduct, an therefore comes clearly within t e scope of my present invention.

The present application comprehends the finished product is derived.

'In the practice of my process I prefer to take of magnesium silicate or of aluminium silicate or the substantial equivalents of either or both in finely comminuted or pulverulent form one hundred (100) parts, by weight, and of water-glass, sodium silicate, or potassium silicate in fluid form twenty (20) parts, by weight. The proportlons spec fied may be varied by increase of the proport1onate quantity of water-glass, the efi ect thereof being to vary the composition of the product so as to obtain the degree of hardness and density or compactness sought; but for genas a possible variation in te, which, whileit may not enter into or interfere with the chemical combination in any wise may be regarded as an adventi- 1310118 quantitythat is to say, a substance that is wholly inert my compound. or v eral purposes I find it desirable and prefer,

as specified, to use substantially the pro ortions stated. The owdered and liqui ingredients are then t oroughly mixed in any suitable manner by machinery or otherwise to a fictile, plastic, or semiplastic mass, if the last term be deemed more accurate, of about the consistency of workable putty. The pulverulent form of steatite is regarded as ture.

herein, in view of the suggested possibility ofv that form of it most favorable to the perfect commingling of the components of the mixture; but if any other form might be found to serve that purpose equally well it would come 'withinthe purview of my. preference.-

The aforesaid commingled mass of materials v is distinctively designated herein the mix- In some of the claims'and elsewhere substitution of different components of the mixture for those specified as preferred and the variability-of the relative proportions thereof and now and then for other obvious reasons, I discard the use of: the definite article and employ the term a mixture to designate the oommingled components.

- When the ingredients have been thoroughl commingled and reduced to desirable ficti ity'that is to say, to a condition suitable for molding or therwise fashioning'itinto shapeit is preferably subjected'to great pressure, as in ahydraulic or other powerful press. The pressure may be applied to the fictile or plastic mass of the mixture either in the act of im arting to it the shapeultimately desire or in forming it into a blank preparatorto its being subsequently out or otherwise ressed to conform to any preferred design. The application of pressure to the lastic or fictile mass of the mixture is calcuated to impart to it that degree of homogeneity which is always desirable and which is in many instances essential'in insulators and insulating or refractory material. In the manufacture of certain articlessuoh, 'for example, as those of hollow o1 tubular formit is practicable by the employment of such presses pirovided with suitable nipples, as are fam ar in the'fictile art, to impart to the said articles at one and the same.

. time and in one operation the desired shape fand requisite degree of density. In other instances it ispracticable'only to compressthe mass into a blank of the right density, reserving the final shaping of it toa later period in the manufacture, as hereinafter more par-' -ticularly specified. After .the mixture .of

components has been treated in the manner" specified it is then dried, which may bev accom lished by placing it in any suitable'drylnfor example, one heated by steam.

ing- As it comes from the drying-kiln the mixture is in that'state which may be-for convenience termed .greenthat is to say, it'is of about the consistency of massive talc or native steatite andis in condition for dressing, rubbing, smoothing, drilling, tapping, mitering, grooving, many other manual or mechanical.op-.

. eration necessary to or desirable for the completion or finishmg of the article so far as shaping of it is considered. In other words,

the mixture always remains throughout and after the drying step of the process in a formative and workable state, a quality which is lost in the compound, one of whose important characteristics isextreme hardness, a hardnesswhich may be made such as to resist the action of any ordinary cutting- ,tool. That final step. of the process by which .the conversion to my compound of a mixture having steatite for its base is effected consists in subjecting for a requisite period of time the article formed from a mixture of suitable components, as specified, and in the green or kiln-dried state toa temperature at which the desired reaction and the conversion of the green mixture to the finished materialthatis to say, to my compound-will take-place. The temperature atwhich the change in the character of the green mixture to that of my compound occurs may be varied somewhat, variation in temperature being dependent upon various changes in conditionssuch, for example, as in the components or proportions employed the mixture. The reaction by which the mixture is converted. to my compound begins to occur at about 7 00 centigrade and upward, and it appears to de end upon an elevated tempera ture rather t an upon the length of time of exposure. Experience has shown the reaction to be complete andthe best results to be obtainableunder condition stated in the last sentence of this paragra h at about 1, 500

exposure may be.

centigrade. The time o varied and is dependent inpart u on the bu of the mass that is being treate In actual manufacture I employ a temperature of' from 1,500 to 2,000 centigrade for a period determinable upon tests repeated at'intervals during the firing, but usually of fromfive to eight hours. Laboratory testsupon comparatively minute articles have shown the best results to be obtainable by a five minutes exposure to a temperature. of about 1,500 centigrade.

It has been specified thatthe baseto wit, 7

steatite or its equivalent employe d inthe 'mixture" for the manufacturej'of my compound used in pulverulent or like suitable form. An obvious advantage derived from ufacture of articlesat reduced cost as compared with manufactures thereof from massive steatite, but also in very many instances it renders possible the manufacture of articles which could not in any wise be produced from massive steatite by any'of the known ICO such use has been'specified to be the perfect methods of worln'ng it. By way of example,

particular reference -,may be made to the manufacture of hollow or'tubularforms of any desired longitudinal dimensions, which is now being carried on by means of my process. Bythe aid of my process minute tubes, such as it appears cannot be: made without 'it' and which are of extensive utilityin different arts,- may be produced out limitation as to length.

"It has been specified thatmy compound is a complex anhydrous bisilicate, and as indicating the lines of substitution in the prac-. tics of my process previously referred to,

practically withof different components of the mixture for those s ecified t e following suggestions are deeme to be important. vIt ap ears that my compound is a silicate in who the oxygen ratio of basic oxids to silica is as one to two and that it is therefore .a complex bisilicateyas specified. In anygiven complex,

considered with'reference to its basic radi-'- cals, it is theoretically acceptableithat any other radical having equal valence may replace each of the radicals present. For in-- stance, potassium, lithium, and other members of a group will replace sodium; barium,- strontium, and other members of another group will-replace magnesium and calcium;

c omium, manganese, and like elements Wlll replace aluminium and iron. Even the potasslum may replace the aluminium; but

it would take three atoms of potassium to replace one atom of aluminium.' Another variation suggests itself as a ossible alternative. In addition to the hydrous magnesium and aluminium silicates mentioned (of which talc, pyroph llite, and other bisilicates are examples) we ave in nature a class of.

unisilicates. To this class belongs serpentine, which a h drous silicate of magnesium containing a larger percentage of magnesium than talc does and therefore less percentage of silica.

Considering the various ste s of my proc: ess and the product obtaine froma scientific point of view, the suggestion readily occurs that by supplyingxthe deficiency of sllica in one of the components of the mixture by excess thereof in another any of the unisilicates may be employed in my process.

For instance, in combination with serpentine it might be feasible to use in preparing a suit able mixture for carrying out my process a glass richer in silica than ordinary waterglass, or the result might be reached by makmg the mixture of the basic material waterglass and silica.-

While in'tlie fore oing specification I have indicated by way of suggestion certain possible variations in my process, yet I wish it to be distinctly understood that in the preparation of the mixture used in the practice of my process I regard magnesium silicate and sodium silicate as the unquestionably-available components of the mixture. Whatever is predicated of the mixture of those com onentsto wit, of steatite and water-g ass and of the compound derived therefromis founded upon actual experience in extensive and long-continued use of the same in manufacture of my product forcommercial urposes. Said mixture constitutes, there ore, the standard with which proposed substitutes must be compared in order to determine their equivalency or non-equivalency for employment in my process. The suggestions of equivalents and variations, while they are founded partly u'pon general knowledge in the art and artly upon experimental use, are oifered, or the most part, as h otlieses the truth of which ma be verified m .practice.

Articles made o m fore described may, referred, for the sake of ornamentation or -ot er reasons be by the use of an suitable-enamel, such as that used on porce ain or kaolin ware, provided with a surface glaze.

Wl1at I claim is-.- 1. The process which consists in the conversion of a mixture of hydrous silicates in convertible proportions into a complex anhydrous bisi 'cate through the appllcat1on of heat.

2. The rocess which consists in the conversion of a mixture of magnesium silicate and sodium silicate or their e uivalent into a complex anhydrous bisilicate by the application of heat.

3. The process which consists in the conversion of a mixture of steatite and Waterglass or their substantial e uivalents in convertible proportions, by t e application of heat, substantially as specified.

4. The process which consists in subjecting, for a requisite period of time, a mixture of suitably-constituted material having steatite forits base to a tem erature at which the desired reaction and t e conversion of the mixture to my compound will take place.

5. The process which consists producing a complex anhydrous bisilicate by prepar ng a mixture of hydrous silicates and sub'ectmg the same to a temperature at which t e necessary reaction occurs, substantially as spec1- fied.

6. The process which consists ofpreparing a mixture of hydrous silicates in suitab e proportions and in subjecting saidnuxture to a temperature at which the reactlon necessary to its conversion occurs, substantially as and for the purpose specified.

7. The process which consists in preparing a mixture of magnesium and sodium sihcates and in effecting reaction therein upon the application of heat at a temperature necessary to the conversion of the mixture.

. 8. The process of producing an insulating and refractory compound, the same being a complex anhydrous bisilicate having for its compound as hereto essential constituents silica with sodium and In testimony wherecf I have hei eunto magnesium oxlds, which consists in subject signed my name in the presence of two subing, for a requisite period of time, a mixture scribing Witnesses.

,of suitable components, having steatite for V DEMETRIUS M. STEWARD- 5 its base, to a temperature at'which the reaG- witnesses t tion necessary to the conversion, of the mix- W. M; VICKERB,

ture to the compound will take place. I W; H. DE WITI. 

